Explain the basic logical Vue.js app organisation

A Vue.js application consists of a root Vue instance created with new Vue, optionally organized into a tree of nested, reusable components. For example, a todo app’s component tree might look like this:

Root Instance
└─ TodoList
   ├─ TodoItem
   │  ├─ DeleteTodoButton
   │  └─ EditTodoButton
   └─ TodoListFooter
      ├─ ClearTodosButton
      └─ TodoListStatistics

All Vue components are also Vue instances.